A sheet metal annulus has general utility when the structure has to be reinforced to obtain resistance to bending. It may, for example, be used as a tank baffle or as the end or head of a reel. In the latter case, an annulus for a reel or the like of heavy construction has usually been formed in arcuate sections with the corrugations in the sections and then several pieces of sections have been welded together to form an annulus as is shown in British Pat. No. 1,187,651 published Apr. 15, 1970. In other instances a strip of metal has been crimped with rectangular formation corrugations of uniform depth and then the outer surfaces of these corrugations have been brought together by folding in a second step to give a circular formation for a reel head where the head is then a complete annulus but formed in two steps as in U.S. Pat. No. 2,928,623. Other variations have also been tried such as corrugating a circular blank as seen in U.S. Pat. No. 3,736,787.